package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

        @Resource
        private ISeckillVoucherService seckillVoucherService;
        @Autowired
        private RedisIdWorker redisIdWorker;
        @Autowired
        private StringRedisTemplate stringRedisTemplate;
        @Resource
        private RedissonClient redissonClient;

        /**
         * 秒杀优惠券
         *
         * @param voucherId
         * @return
         */
        // 定义一个静态的 Redis Lua 脚本对象，用于原子性执行秒杀逻辑
        private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

        // 静态代码块，用于初始化 Lua 脚本对象
        static {
            // 创建一个 DefaultRedisScript 对象
            SECKILL_SCRIPT = new DefaultRedisScript<>();

            // 设置 Lua 脚本的路径，脚本文件位于类路径下的 "seckill.lua"
            SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));

            // 设置 Lua 脚本的返回值类型为 Long 类型
            SECKILL_SCRIPT.setResultType(Long.class);
        }
        // 创建 单线程线程池确保订单处理的顺序性，避免并发问题
        private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

        // 用于初始化异步订单处理线程
        @PostConstruct //表示在当前类依赖注入完成后执行
        private void init() {
            // 提交订单处理任务到线程池
            // VoucherOrderHandler 是一个持续运行的任务，会不断从阻塞队列中获取订单并处理
            SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
        }

        //开始线程任务
        private class VoucherOrderHandler implements Runnable {
            String queueName = "stream.orders";
        @Override
        public void run() {
//            // 初始化消费者组
//            try {
//                // 创建消费者组，如果组已存在则忽略错误
//                stringRedisTemplate.opsForStream().createGroup(queueName, "g1");
//            } catch (Exception e) {
//                log.warn("消费者组 g1 已存在，跳过创建");
//            }
            while (true) {
                try {
                    // 1.尝试监听队列，获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.orders >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2.判断消息获取是否成功
                    if (list == null || list.isEmpty()) {
                        // 2.1 如果不存在，获取失败，说明没有消息,继续下一次循环
                        continue;
                    }
                    // 3.解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                    // 4 如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);

                    // 5. ACK确认  SACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());

                } catch (Exception e) {
                    log.info("处理订单异常", e);
                    handelPendingList();
                }
            }
        }

        private void handelPendingList() {
            while (true) {
                try {
                    // 1.获取 pending-list 中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 STREAMS stream.orders 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );

                    // 2.判断消息获取是否成功
                    if (list == null || list.isEmpty()) {
                        // 2.1 如果不存在，获取失败，说明pending-list没有消息,结束循环
                        break;
                    }

                    // 3.解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                    // 4 如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);

                    // 5. ACK确认  SACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());

                } catch (Exception e) {
                    log.info("处理pending-list异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        }
    }
        //  创建订单
        private void handleVoucherOrder(VoucherOrder voucherOrder) {

            // 1.获取用户
            Long userId = voucherOrder.getUserId();

            // 2. 创建分布式锁对象
            RLock lock = redissonClient.getLock("lock:order:" + userId);

            // 3.获取锁
            boolean isLock = lock.tryLock();

            // 4.判断获取锁是否成功
            if (!isLock){
                //获取锁失败,返回或重试
                log.info("不允许重复下单");
                return;
            }
            try {
                // 调用下单方法
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                //释放锁
                lock.unlock();
            }
        }
        //代理对象
        private IVoucherOrderService proxy;
        @Override
        public Result seckillVoucher(Long voucherId) {
            //获取用户id
            Long userId  = UserHolder.getUser().getId();

            //获取订单id
            long orderId = redisIdWorker.nextId("order:");

            //1.执行Lua脚本
            Long result = stringRedisTemplate.execute(
                    SECKILL_SCRIPT,
                    Collections.emptyList(),
                    voucherId.toString(), userId.toString(),String.valueOf(orderId)
            );
            // 2.判断结果是否为0
            int r = result.intValue();
            if ( r != 0){
                //2.1 不为0 没有购买资格
                return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
            }
            // 3.获取代理对象
            proxy = (IVoucherOrderService) AopContext.currentProxy();

            // 4.返回订单id
            return Result.ok(orderId);
        }
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 5. 一人一单
        Long userId = voucherOrder.getUserId() ;

        // 5.1 查询订单,查询当前用户是否已经购买过该优惠券
        int count = query().eq("user_id", userId)
                .eq("voucher_id", voucherOrder.getVoucherId()).count();

        // 5.2 一人一单 判断
        if (count>0){
            //用户已经购买过了
            log.info("用户已经购买过一次");
            return;
        }
        //6.乐观锁扣减库存,确保只有在库存大于0时才能进行扣减，防止超卖
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock -1
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock",0)// where id =? and stock > 0?
                .update();
        if (!success){
            //扣减失败
            log.info("库存不足");
        }
        // 7.保存订单至数据库
        save(voucherOrder);

    }
}


























